In a known manner, rotary electrical machines comprise a stator and a rotor which is integral with a shaft. The rotor can be integral with a drive shaft and/or a driven shaft, and can belong to a rotary electrical machine in the form of an alternator, an electric motor or a reversible machine which can function in both modes.
The stator is fitted in a housing which is configured to rotate the shaft, for example by means of bearings. The stator comprises a body provided with a plurality of teeth which define notches, and a winding which is inserted in the notches of the stator. The winding is obtained for example from continuous wires covered with enamel, or from conductive elements in the form of pins connected to one another by welding. Alternatively, the phases of the machine are formed from individual coils which are each wound around a stator tooth. The phases connected in the form of a star or a triangle comprise outputs which are connected to an electric control module.
In addition, the rotor comprises a body formed by a stack of sheets of plates held together in the form of a set by means of a suitable securing system. The rotor comprises poles which are formed for example by permanent magnets accommodated in cavities, each delimited by two adjacent rotor teeth.
Variation of the torque supplied is observed around the average torque of the machine. This variation of torque is caused by the interaction between the rotor and the stator, and depends in particular on the magnetic saturation of the machine. This variation of torque gives rise to problems of noise, in particular when the electrical machine is coupled to an external element by means of a gear.